Some newer Intel Skylake based Dell laptops with Win8 precision touchpad fail when initial feature reports are fetched from it. Below is an example output with some additional debug included: i2c_hid i2c-DLL0704:01: Fetching the HID descriptor i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=20 00 i2c_hid i2c-DLL0704:01: HID Descriptor: 1e 00 00 01 99 02 21 00 24 ... ... i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 38 02 23 00 i2c_hid i2c-DLL0704:01: report (len=4): 04 00 08 05 i2c_hid i2c-DLL0704:01: report id 13 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 3d 02 23 00 i2c_hid i2c-DLL0704:01: failed to retrieve report from device. i2c_hid i2c-DLL0704:01: report id 7 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 37 02 23 00 i2c_hid i2c-DLL0704:01: report (len=259): 03 01 07 fc 28 fe 84 40 ... i2c_hid i2c-DLL0704:01: report id 4 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 34 02 23 00 We manage to fetch few reports but then the touchpad dies: i2c_designware i2c_designware.1: i2c_dw_handle_tx_abort: lost arbitration i2c_hid i2c-DLL0704:01: failed to retrieve report from device. it eventually pulls the whole I2C bus low: i2c_designware i2c_designware.1: controller timed out i2c_hid i2c-DLL0704:01: failed to set a report to device. Fix this by preventing initial feature report retrieval for Win8 devices. Instead we fetch reports as needed in mt_feature_mapping(). This prevents fetching reports which might cause problems with the device in question. Suggested-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- This is a second version. The first one which just prevented initial report reading can be found here: https://lkml.org/lkml/2015/9/24/191 This version tries to do what Benjamin suggested by reading feature values as needed in mt_feature_mapping(). This fixes the issue in the Dell laptop I have here. drivers/hid/hid-multitouch.c | 42 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index 661b4fce1a5d..d9ca2b96ab68 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -309,6 +309,38 @@ static struct attribute_group mt_attribute_group = { .attrs = sysfs_attrs }; +static void mt_get_feature(struct hid_device *hdev, struct hid_report *report) +{ + int ret, size = hid_report_len(report); + u8 *buf; + + /* + * Only fetch the feature report if initial reports are not already + * been retrieved. Currently this is only done for Windows 8 touch + * devices. + */ + if (!(hdev->quirks & HID_QUIRK_NO_INIT_REPORTS)) + return; + + buf = hid_alloc_report_buf(report, GFP_KERNEL); + if (!buf) + return; + + ret = hid_hw_raw_request(hdev, report->id, buf, size, + HID_FEATURE_REPORT, HID_REQ_GET_REPORT); + if (ret < 0) { + dev_warn(&hdev->dev, "failed to fetch feature %d\n", + report->id); + } else { + ret = hid_report_raw_event(hdev, HID_FEATURE_REPORT, buf, + size, 0); + if (ret) + dev_warn(&hdev->dev, "failed to report feature\n"); + } + + kfree(buf); +} + static void mt_feature_mapping(struct hid_device *hdev, struct hid_field *field, struct hid_usage *usage) { @@ -327,6 +359,8 @@ static void mt_feature_mapping(struct hid_device *hdev, break; case HID_DG_CONTACTMAX: + mt_get_feature(hdev, field->report); + td->maxcontact_report_id = field->report->id; td->maxcontacts = field->value[0]; if (!td->maxcontacts && @@ -343,6 +377,7 @@ static void mt_feature_mapping(struct hid_device *hdev, break; } + mt_get_feature(hdev, field->report); if (field->value[usage->usage_index] == MT_BUTTONTYPE_CLICKPAD) td->is_buttonpad = true; @@ -1029,8 +1064,13 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id) * reports. Fortunately, the Win8 spec says that all touches * should be sent during each report, making the initialization * of input reports unnecessary. + * + * In addition some touchpads do not behave well if we read + * all feature reports from them. Instead we prevent + * initial report fetching and then selectively fetch each + * report we are interested in. */ - hdev->quirks |= HID_QUIRK_NO_INIT_INPUT_REPORTS; + hdev->quirks |= HID_QUIRK_NO_INIT_REPORTS; td = devm_kzalloc(&hdev->dev, sizeof(struct mt_device), GFP_KERNEL); if (!td) { -- 2.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
